DE2820886A1 - CARBURETTORS FOR COMBUSTION MACHINERY - Google Patents

Description

282088S

HITACHI, LTD., Tokyo, Japan

Carburettors for internal combustion engines

The invention "relates to a carburetor for Internal combustion engines, in particular to an improved starting device for a carburetor of the type a starting intake line for supplying a fuel-air mixture to the started and heated one Having internal combustion engine, in addition to a main intake line for supplying a fuel-air mixture to the engine after it has finished heating.

A carburetor with a main suction line and a starting suction line is already known (see JP utility model publication No. 12822/77). This carburetor

809847/0883

essentially comprises a main intake line, a throttle valve arranged therein, a main fuel line for the main intake line, a main air duct for the main fuel line, a starting intake line, a starting fuel line for supplying fuel to the starting intake line, and one in the Starter or switching valve arranged on the start suction line. If with this carburetor the degree of opening the throttle increases before the started engine is fully warmed up, the increases Suction pressure in a section of the main suction line that is downstream of the throttle valve, where there is the start suction line opens into the main suction line. This results in a reduction in the amount of fuel-air mixture supplied through the starting intake pipe, and as a result, it becomes the engine supplied mixture lean even when the throttle valve is open, so that the fuel through the Main fuel line can be fed. So that becomes The mixture supplied to the engine is too lean to properly operate the not yet fully warmed up engine to operate. As a result, an interruption problem arises during the operation of the engine fuel combustion or deterioration in acceleration properties.

To solve this problem, it has been customary to use a Method to be used in which the fuel-air mixture ratio is changed more than necessary to enrich the mixture, thereby expanding the range in which the fuel and

809847/0883

Air proportions of the G-emisch in accordance with a Increase in the amount of intake air can be changed. However, this method has the disadvantage that it does not is inexpensive because the fuel consumption increases in the vicinity of the smallest amount of air, and that the Correction of the air-fuel ratio with exception cannot be carried out satisfactorily in the vicinity of the smallest amount of air.

The object of the invention is to create a carburetor with an improved starting device which also prevents excessive leaning of the fuel-air mixture supplied to the engine when the throttle valve in the main intake line is opened when the engine is still after starting is not fully warmed up.

This object is achieved in the carburetor according to the invention by a connecting line which has a section the starter suction line, which is connected upstream of the starter valve, with a section of the main air duct connects, the latter section being connected upstream of the main air nozzle.

By providing the connecting line, the following effect is achieved: When the motor is opened by opening the The throttle valve is accelerated when it is not fully warmed up, which increases the engine supplied air volume. In this case, an increase in the suction pressure causes a decrease in the amount of the power supplied through the start suction line

809847/0883

substance-air mixture. The suction pressure of the starting suction line however, is transmitted to the portion of the main air duct which is prior to the inlet end of the main air nozzle and thereby the amount of air withdrawn is reduced and that through the main intake line The fuel-air mixture supplied to the engine is substantially uniformly enriched. Thus becomes the engine is supplied with a fuel-air mixture with a mixture ratio that is necessary for the operation of the started, but not yet fully warmed engine is suitable, whereby the previously explained Disadvantages of known carburetors are eliminated.

The invention thus provides a carburetor for internal combustion engines indicated, with a main suction line having a throttle valve and a Start suction line, in which a switching or starter valve is arranged and one end of which is in a section of the main intake line opens, which is connected downstream of the throttle valve, wherein a Main fuel line and a main air duct with a main air nozzle for the main fuel line the main suction line are provided. A connecting line connects a section of the starting suction line, which is connected upstream of the starter valve, with a section of the main air duct that the Main air nozzle is connected upstream. When the throttle valve is opened to accelerate the engine, before the engine is fully warmed up after starting, this arrangement creates the suction pressure

809847/0883

τοπ of the starting suction line transmitted through the connecting line to the inlet side of the main air duct, so that the fuel-air mixture supplied through the main intake line with essentially can be enriched at a constant rate.

An embodiment of the invention is explained in more detail below with reference to the drawing. It demonstrate:

Pig. 1 is a vertically sectioned side view of an "already developed Carburetor;

2 shows the relationship between the amount of air and the fuel-air mixture; and

Fig. 3 is a vertically sectioned side view of the carburetor according to the invention.

The "already developed carburetor of FIG. 1 includes a main suction line and a starting suction line.

In particular, the carburetor 1 comprises the main suction line 2 and the starting suction line 3. In the main suction line 2, a throttle valve 5 is pivotably mounted on a valve spindle 4. The start intake

809847/0883

2820888

Line 3 has a starter air nozzle 6 which is arranged at the inlet end of the starter intake line is, and opens at its outlet end in a section 7 of the main intake line 2, which is connected downstream of the throttle valve 5. A switching or Starter valve 8 is arranged in the middle of the start suction line 3 and works so that it the Start suction line 3 opens when the engine is started and warmed up.

A float chamber 9 is on one side of the main suction line 2 and a mixing cylinder 11 running through a main fuel nozzle 10 arranged, which has a main air nozzle 12 at its upper end, which extends into a portion of the Hauptansauglextung 2 upstream of the throttle valve 5 opens. The mixing cylinder 11 is with a Main air duct 13 connected, in which near the mixing cylinder 11 a main air nozzle 14 is arranged; a Yor main air nozzle 15 is at the inlet end of the Channel 13 arranged.

The mixing cylinder 11 is on its suction side with a End of channel 16 kept in communication for partial load operation; the other end of the channel 16 opens through transition bores 17 in a section of the main intake line 2, which is close to the throttle valve 5 lies. The transition bores 17 have the task of providing fuel to the main intake line 2 during partial load operation to feed. The channel 16 for partial load operation has at its inlet-side end section a partial

809847/0883

_ 9 -

load nozzle 18, and near the transition bores an idle nozzle 19 is arranged. An idle hole 20 for idle operation is on duct 16 in a position downstream of the idle nozzle 19 provided.

Adjacent to the part-load line 16 is a line which supplies fuel to the engine when it is started feeds and is connected at one end to the start suction line 3. Usually the connection blocked by the starter valve 8 between the line 21 and the starter suction line 3. A starter nozzle 22 is arranged at the other end of the line 22. A portion of the main air duct 13, which is on the inlet side The end of the main air nozzle 14 is connected to the partial load line 16 by a line 23, in the middle a part-load air nozzle 24 is arranged.

In the case of the carburettor constructed in this way, the quantity of the fuel-air mixture is regulated by opening it and closing the throttle valve 5. In part-load operation, the fuel from the part-load nozzle 18 is downstream the main nozzle 10 is sized, the main suction line 2 through the transition bores 17 and the Idle bore 20 supplied. This type of carburetor has a fuel-air mixture ratio corresponding to the solid line curve A in FIG. 2 when the starting intake pipe 3 is not in operation after the engine has warmed up.

809847/0883

The fuel-air mixture, one left on and one more However, if the engine is not fully warmed up, it must be fatter than after the engine has finished warming up. For this purpose, the one located in the starting suction line 3 is used Starter valve 8 is open, so that the starter intake line 3 is supplied with a richer fuel-air mixture the mixing ratio is brought to a value that is necessary for starting and warming up the engine is. The enriched air-fuel mixture supplied in this way is fed through the main intake line 2 supplied fuel-air mixture supplied, so that the fuel-air mixture supplied to the engine overall is enriched to a value that is necessary for starting and warming up the engine is.

However, if the opening degree of the throttle valve 5 increases before the engine has finished warming up, then the suction pressure increases and causes a decrease in the pressure difference between the inlet and the Outlet side of the starting suction line 3. This has a reduction in the amount supplied through the starting suction line 3 Fuel-air mixture amount result, and for this reason, the fuel-air mixture supplied to the engine emaciated. So even if the increasing degree of opening of the throttle valve 5 a a certain amount of the fuel-air mixture is supplied through the main nozzle 12, is the total supplied The fuel-air mixture is leaner than that required for operation of the not yet fully warmed-up engine required fuel-air mixture. As a result, there arises a problem that fuel combustion temporarily stops or the ability to accelerate deteriorates.

809847/0803

2820386

To solve this problem, it has hitherto been customary to compensate the fuel-air ratio for the smallest amount of air more than necessary, as indicated by curve B in FIG Range is expanded in which it can be compensated for as the amount of intake air increases. However, this method is uneconomical because the fuel consumption increases near the smallest amount of air. Furthermore, there is the following disadvantage in a region excluding the lowest amount of air: Ylenn. As the degree of opening of the throttle valve 5 increases to increase the amount of intake air beyond the range shown by the curve B in which the air-fuel mixture is compensable, the air-fuel mixture ratio becomes similar to that obtained when the warming-up of the engine has ended (see curve A in FIG. 2). The fuel-air mixture is thus leaner than the fuel-air mixture required for an engine that has not yet been fully warmed up, and the problem of insufficient enrichment of the mixture in the air volume range beyond curve B arises again.

In the carburetor according to FIG. 3, which is a preferred embodiment represents, a connecting line 25 is provided, which is a portion of the main air duct 13 of the fuel system for the main intake line 2, this section of the main air nozzle 14 and also the part-load air nozzle 24 in the line 23 upstream is connected to a section of the starter intake line 3, which is connected upstream of the starter valve 8. One

809847/0883

Compensating bore 26 is arranged in the middle of the connecting line 25.

In this embodiment, when the throttle valve 5 is opened and the amount of intake air increases by accelerate the engine before it is fully warmed up, but immediately after starting it same, the suction pressure from the start suction line 3 to sections of the main air duct 13 and the line 23, which are located in front of the inlet of the main air nozzle 14 or the partial load air nozzle 24, transferred, and the pressure difference between the inlet and outlet sides of each air nozzle 14 and 24 is reduced. As a result, the amount of air removed is reduced, so that the air supplied through the main intake line 2 to the engine Fuel-air mixture can be enriched essentially uniformly.

So even if the throttle valve 5 is essentially fully open and the amount of intake air is maximized becomes, it is possible to compensate the fuel-air ratio in the mixture in such a way that the Mixture enriched over essentially the entire area of the air volume or the throttle valve opening (cf. curve C in Pig. 2, which is obtained when the starter valve 8 is opened while the Warming up of the engine has not yet ended). The engine can therefore be accelerated smoothly even if it is not yet fully warmed up, which causes the disadvantages of this type of carburettor explained above to be overcome.

809847/0883

A compensation of the fuel-air ratio of a mixture relative to the intake air quantity can take place in a desired manner in that the design data for the Yor main air nozzle 15, the Starter air nozzle 6 and the compensating bore 26 can be selected in a suitable manner.

Therefore, when the compensation of the air-fuel mixture ratio of a mixture is set using curve A of Pig. 2 is used, which shows the mixing ratio, that is obtained when the starter valve 8 is closed after the engine has fully warmed up, can set a maximum value for the compensation of the air-fuel mixture ratio a mixture can be achieved. Thus, fuel consumption can be made more economical by using a suitable Fuel-air mixture ratio is selected, and the engine can run smoothly without fuel stoppages or worse Acceleration properties occur.

With this carburetor, the fuel-air mixture ratio shifts from curve C to curve A when the starter valve 8 after completion of the heating the motor is closed.

From the above explanation it can be seen that in a carburetor with a main intake line and a start intake line a connecting line is provided, which is in front of the inlet of the main air nozzle for the main fuel line the main suction line

809847/0883

2820386

Cut the main air line with a section of the starter intake line, which is in front of the inlet of the starter valve lies, connects. This arrangement has the very good effect that when the door is open Starter valve, the negative pressure generated in the starter intake line during the warm-up of the engine Section of the main air duct is brought into action, which is in front of the inlet of the main air nozzle for the Main fuel system is so that even when the throttle valve is open in the main intake line the The fuel-air mixture in the main intake does not become excessively lean compared to that for the fully warmed-up engine required fuel-air mixture.

809847/0883

Blank page

Claims (3)

Expectations M \ carburettor for internal combustion engines, with a main intake line, a throttle valve arranged therein, a main fuel line for the main intake line, a main air duct in which a main air nozzle for the main fuel line is arranged is, a starting intake line, a starting fuel line for fuel supply to the starting suction line, and a starter valve arranged in the starter intake line, marked by a connecting line (25) which connects a section of the starter suction line (3) upstream of the starter valve (8) is connected to a section of the main air duct (13), the latter section of the main air nozzle (14) is connected upstream. 2. Carburetor according to claim 1,
characterized, that a compensating nozzle (26) is arranged in the middle of the connecting line (23). 81- (A 2987-02) -schö 809847/088 2820386 3. Carburetor according to claim 1 or 2, with a part-load fuel line opening into the main fuel line and with a part-load air duct arranged in the part-load fuel line and connected to the main air duct, characterized, that one end of the 7 "connecting line (25) in the Main air duct (13) opens at a point which is the inlet of a part-load air nozzle (24) in the part-load air duct (23) is connected upstream. 809847/0883